Large volumes of reinforced fiberglass polymers (FRP), or simply fiberglass, are produced annually for a wide range of applications due to their properties, such as corrosion resistance in aggressive environments, good tensile and flexural strength, and low weight. The increase in demand and consequent growth in its production have resulted in an increase in the quantity of fiberglass waste. This waste represents a major challenge for the industry in terms of waste management. Currently, most of this waste is disposed of in landfills, generating high economic and environmental costs.
This situation has encouraged the productive sector to endeavor efforts for the development of new processes for fiberglass recycling. The main recycling processes for these composites can be divided into: a) incineration, with or without partial heat recovery of the combustion of the polymeric fraction; b) chemical or thermal recycling for elimination of the organic portion and reuse of the fibers; and c) mechanical recycling through comminution in order to fragment the material to the particle size of interest and then reuse it as an element in new composite materials. This latter recycling process has the advantage of not producing any type of pollutant, whether gases or solvents, unlike the first two processes.
This invention proposes the use of mechanically-recycled fiberglass waste in wholesale substitution of conventional coarse aggregates in the production of high-tech concrete, which can be used as a thermo-insulation barrier for refitting and thermal comfort, intended for construction industry.
Concrete is a composite material basically consisting of water, cement and small and coarse aggregates, which may or may not comprise additives for specific purposes, such as plasticity on fresh cement and delaying hardening, among others. This invention proposes to completely replace conventional coarse aggregates with fiberglass properly comminuted.
The use of recycled fiberglass in the production of concrete as a partial substitute for small aggregates is already described in the state of the art. Osmani et al. (2010) reveals a study of the use of pulverized fiberglass waste as part of the fine aggregate in the production of concrete. In this study, hundreds of specimens were tested with the replacement of 5% to 50% of the fine aggregate (sand) with recycled fiberglass powder. The best results, in terms of mechanical properties, corresponded to only 5% and 15% substitution. The study used only a small proportion of fiberglass. In addition to this, the recycled fiberglass must be finely pulverized before being used in the production of the concrete.
Correa et al. (2011) also reveals a series of tests to confirm the behavior of the concrete where part of the fine aggregate is replaced by pulverized fiberglass. The experiments replaced 5 to 20% of the fine aggregate (sand) with recycled fiberglass with particle size less than 63 μm. Test specimens were produced with the addition of a superplasticizer. The results obtained also indicate an optimum proportion of 5% substitution, where the reduction in the mechanical strength of the concrete is less significant.
Asokan et al. (2010) reveals a battery of experiments with concrete containing pulverized recycled fiberglass with the aim of improving the mechanical properties of this type of concrete. Good results were obtained with the addition of 2% of a superplasticizer (polycarboxylate) for a substitution of only 5 to 15% of the fine aggregate by the fiberglass waste.
Although the studies cited obtained satisfactory results for the performance of the concrete produced with fiberglass, they reveal, in all cases, that there is a need to use fine particle fiberglass, which significantly increases the cost of the process. In addition to this, the fiberglass waste is incorporated only as a small portion of the fine aggregates.